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Rifampin Concentration in Serum

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of rifampin, a medication used to treat certain bacterial infections like tuberculosis, in your blood serum.

Quick summary

["Rifampin levels help ensure the drug is working at the right dose for your condition."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
25200-7
Short code
Rifabutin Islt Slgr Mcbct AB 2.0
Synonyms
Rifabutin Islt Slgr Mcbct AB 2.0
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
method-for-slow-growing-mycobacteria-antibiotic-concentration-at-ug-ml
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’re taking rifampin to treat an infection. It helps monitor whether your dose is effective and safe, especially if you have kidney problems or take other medications that could interact with rifampin.

How the Test Works

A blood sample is taken from a vein in your arm. The lab uses a sensitive test to measure how much rifampin is present in your serum, often through a chemical reaction that detects its presence.

What to Expect Before the Test

No special preparation is usually needed, but let your provider know if you’re on blood thinners, have kidney issues, or are pregnant. Avoid eating or drinking for 2 hours before the test if instructed.

What to Expect During the Test

You’ll lie down while a nurse inserts a needle into your arm to draw blood. The process takes a few minutes, and you may feel a brief pinch. The sample is then sent to the lab for analysis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Low rifampin levels may indicate the drug isn’t working well, while high levels could signal toxicity or improper dosing. Regular monitoring helps adjust your treatment to avoid side effects like liver damage or rash.

Short name

Rifampin Level

Frequently asked questions

How often will I need this test?
Your provider will determine the timing based on your treatment plan, infection type, and other medications. It may be done weekly or monthly, depending on your specific case.
What does a normal or abnormal result mean?
Results aren’t interpreted alone—they’re compared to your medical history and symptoms. A low level might mean your dose needs adjustment, while very high levels could require stopping or changing medications.
Can I eat or drink before this test?
Follow your provider’s instructions, but generally, avoid food/drink for 2 hours before the draw to get an accurate reading.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy